The invention is directed to the field of energetic materials known as poly(N-nitro) dodecane cage compounds and processes to prepare these materials. In particular this invention relates to hexa(N-Nitro),hexaazatetracyclic dodecane compounds which are described in IUPAC nomenclature as 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.0.sup.5,9.0. sup.3,11 ]dodecanes. The parent compounds and corresponding skeleton structures have the common name of isowurtzitane. The skeletons are abbreviated as -HISW; the hexanitrohexaazaisowurtzitanes are abbreviated as HNIW; the compounds and the use of the nomenclature are described in U.S. Pat. No. 5,693,794.
The HNIW compounds have a density of about 2.0 g/cc and six nitro groups per molecule. The compounds are polymorphic with at least four crystal forms: alpha, beta, gamma and epsilon. Epsilon HNIW has the highest density. Typically the processes of production will result in the alpha HNIW which is then converted to the epsilon HNIW, see CA, Vol 128, NO. 128, No. 14, p. 595, 167451w, Kawabe, et al, 1998. The product in the epsilon crystal form is preferred for use in energetic compositions such as propellants and explosives. The energetic compositions with HNIWs are described as C1-20 containing compositions in U.S. Pat. Nos. 5,712,511, and 5,739,325. The preferred usage is to apply this term to the epsilon form of HNIW.
There are problems in developing compositions which utilize the epsilon HNIW as an energetic material. The intermediate HNIW crystal forms need to be available in high purity and yield. The processes for producing the intermediates need to be simplified. The reactions and reaction media need to reduce or eliminate the presence of side reactions, shock-sensitive impurities, other impurities and oxygenated isowurtzitanes so that a high purity, shock insensitive epsilon HNIW crystal can be obtained. It is to these ends that this invention is directed.